Commit 7c018a90 authored by David Jeffery's avatar David Jeffery Committed by James Bottomley

[SCSI] st: fix memory leak with >1MB tape I/O

There is a memory leak in the st driver when sending large enough reads or
writes using st's direct I/O path.  As part of mapping the application's
memory, a buffer to hold page pointers is allocated and the count of mapped
pages is stored in field do_dio.  A non-zero do_dio marks that direct I/O is
in use.

But do_dio is only 1 byte in size.  Mapping 256 4k pages overflows
do_dio and causes it to be set to 0, like direct I/O option was not
used.  When the I/O completes, the buffer to hold the page pointers is
not freed, and the page counts of the mapped pages are not reduced.
Every I/O of this size then leaks memory.

The size of do_dio needs to be increased to prevent it wrapping around.
Signed-off-by: default avatarDavid Jeffery <djeffery@redhat.com>
Acked-by: default avatarKai Mäkisara <kai.makisara@kolumbus.fi>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent ad07b4a8
...@@ -35,8 +35,8 @@ struct st_request { ...@@ -35,8 +35,8 @@ struct st_request {
/* The tape buffer descriptor. */ /* The tape buffer descriptor. */
struct st_buffer { struct st_buffer {
unsigned char dma; /* DMA-able buffer */ unsigned char dma; /* DMA-able buffer */
unsigned char do_dio; /* direct i/o set up? */
unsigned char cleared; /* internal buffer cleared after open? */ unsigned char cleared; /* internal buffer cleared after open? */
unsigned short do_dio; /* direct i/o set up? */
int buffer_size; int buffer_size;
int buffer_blocks; int buffer_blocks;
int buffer_bytes; int buffer_bytes;
......
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